The vas
deferens is a muscular tube (duct) which carries sperm
cells from the epididymis to the ejaculatory
duct. The muscular wall is remarkably thick in proportion to the
diameter of the lumen. The muscle is organized indistinctly into three
layers -- inner and outer layers of mostly longitudinal smooth muscle fibers
and a middle layer of mostly circular fibers.

The
lumen of the vas is lined by a pseudostratified
columnar epithelium with apical stereocilia, similar to that lining the epididymis.